From patchwork Fri Apr 9 15:53:45 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella X-Patchwork-Id: 42939 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 2609839960F8; Fri, 9 Apr 2021 15:53:57 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 2609839960F8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1617983637; bh=OIk1v3yOyePtKv2ZumNepNCj1LQkffet3mVC64HcMBI=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=d56U8HYvxOI1fHMs8evpWIMRvR3zJMB33PM0ko9hpl/CECQ5iY+yYlqzouLepnztf 9q3RPVWPw2WBIILVGAH1IxF5BlLd+BJs9nfQ5U9n7viJ56eeCdj53Jdg7DJREMxEqh xxrbZVcjBCFsW2diIy+sslJuwF2ZsKUkJe+B/BTg= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-qk1-x72c.google.com (mail-qk1-x72c.google.com [IPv6:2607:f8b0:4864:20::72c]) by sourceware.org (Postfix) with ESMTPS id 3E03B39960E5 for ; Fri, 9 Apr 2021 15:53:54 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 3E03B39960E5 Received: by mail-qk1-x72c.google.com with SMTP id z10so6237992qkz.13 for ; Fri, 09 Apr 2021 08:53:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=OIk1v3yOyePtKv2ZumNepNCj1LQkffet3mVC64HcMBI=; b=DH2NUovdPQnO9Et2sbnYLsvHv3VDpRz6uRsKVyYCaxcex0hSmJfRKZejtj7E+Bbo+M aImcRiBmm5xX2RQhJGihgQJsRrXR9bP6RisgN6dlU6uHAdg97gQ8Ib0jKzVrL3ze+PRu MWKESzVh/o2HXj24U5mYPgRyCHYYErxrZkBgKXoYNWJv1b6RS+BLMfu15RDwjkqu9dau aE3GWYCZkxfd7nz1ZT+FBMhB7bcKLT2EMjDV7Ap1b2BzS+yFaWwfYCLTEAAcQVKLwuzz GcgYceKMKRK6KTZGHpe+X2XaBbGL6hOJs3nPccrNKSjts+v5++1r+3AXOfBXIP5f0iTH cXGw== X-Gm-Message-State: AOAM533Dce0W/CmwGx8hPtCSZlNkoDqgF3w9EOUi/fqFi79oJAaCsiq7 MjrnMC25erVfBKKGYdLePpcFseHmFMfkkCjz X-Google-Smtp-Source: ABdhPJwNSxubVfd7cDdxS+5eeC2BhpdmMLmXSGCvygwSLCi1Lw8Ltlnnp4xYEAV5deO/zuxfeTWqKA== X-Received: by 2002:a05:620a:110a:: with SMTP id o10mr14984386qkk.281.1617983633462; Fri, 09 Apr 2021 08:53:53 -0700 (PDT) Received: from localhost.localdomain ([177.194.41.149]) by smtp.googlemail.com with ESMTPSA id 79sm2087632qki.37.2021.04.09.08.53.52 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Apr 2021 08:53:53 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v3 3/4] linux: Normalize and return timeout on select (BZ #27651) Date: Fri, 9 Apr 2021 12:53:45 -0300 Message-Id: <20210409155346.1357023-3-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210409155346.1357023-1-adhemerval.zanella@linaro.org> References: <20210409155346.1357023-1-adhemerval.zanella@linaro.org> MIME-Version: 1.0 X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Adhemerval Zanella via Libc-alpha From: Adhemerval Zanella Reply-To: Adhemerval Zanella Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" The commit 2433d39b697, which added time64 support to select, changed the function to use __NR_pselect6 (or __NR_pelect6_time64) on all architectures. However, on architectures where the symbol was implemented with __NR_select the kernel normalizes the passed timeout instead of return EINVAL. For instance, the input timeval { 0, 5000000 } is interpreted as { 5, 0 }. And as indicated by BZ #27651, this semantic seems to be expected and changing it results in some performance issues (most likely the program does not check the return code and keeps issuing select with unormalized tv_usec argument). To avoid a different semantic depending whether which syscall the architecture used to issue, select now always normalize the timeout input. This is a slight change for some ABIs (for instance aarch64). Checked on x86_64-linux-gnu and i686-linux-gnu. --- include/time.h | 5 ++++ misc/tst-select.c | 17 ++++++++++++ sunrpc/svcauth_des.c | 1 - sysdeps/unix/sysv/linux/select.c | 44 +++++++++++++++++++++++++------- 4 files changed, 57 insertions(+), 10 deletions(-) diff --git a/include/time.h b/include/time.h index caf2af5e74..e0636132a6 100644 --- a/include/time.h +++ b/include/time.h @@ -502,6 +502,11 @@ time_now (void) __clock_gettime (TIME_CLOCK_GETTIME_CLOCKID, &ts); return ts.tv_sec; } + +#define NSEC_PER_SEC 1000000000L /* Nanoseconds per second. */ +#define USEC_PER_SEC 1000000L /* Microseconds per second. */ +#define NSEC_PER_USEC 1000L /* Nanoseconds per microsecond. */ + #endif #endif diff --git a/misc/tst-select.c b/misc/tst-select.c index 5ad057cd51..534105b500 100644 --- a/misc/tst-select.c +++ b/misc/tst-select.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -47,6 +48,12 @@ do_test_child (void *clousure) int r = select (args->fds[0][0] + 1, &rfds, NULL, NULL, &args->tmo); TEST_COMPARE (r, 0); + if (support_select_modifies_timeout ()) + { + TEST_COMPARE (args->tmo.tv_sec, 0); + TEST_COMPARE (args->tmo.tv_usec, 0); + } + TEST_TIMESPEC_NOW_OR_AFTER (CLOCK_REALTIME, ts); xwrite (args->fds[1][1], "foo", 3); @@ -69,6 +76,16 @@ do_test (void) sc_allow_none); } + if (support_select_normalizes_timeout ()) + { + /* This is handled as 1 second instead of failing with EINVAL. */ + args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 1000000 }; + struct support_capture_subprocess result; + result = support_capture_subprocess (do_test_child, &args); + support_capture_subprocess_check (&result, "tst-select-child", 0, + sc_allow_none); + } + /* Same as before, but simulating polling. */ args.tmo = (struct timeval) { .tv_sec = 0, .tv_usec = 0 }; { diff --git a/sunrpc/svcauth_des.c b/sunrpc/svcauth_des.c index 7607abc818..25a85c9097 100644 --- a/sunrpc/svcauth_des.c +++ b/sunrpc/svcauth_des.c @@ -58,7 +58,6 @@ #define debug(msg) /*printf("svcauth_des: %s\n", msg) */ -#define USEC_PER_SEC ((uint32_t) 1000000L) #define BEFORE(t1, t2) timercmp(t1, t2, <) /* diff --git a/sysdeps/unix/sysv/linux/select.c b/sysdeps/unix/sysv/linux/select.c index 415aa87d3c..8deab751c0 100644 --- a/sysdeps/unix/sysv/linux/select.c +++ b/sysdeps/unix/sysv/linux/select.c @@ -33,12 +33,34 @@ int __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct __timeval64 *timeout) { - struct __timespec64 ts64, *pts64 = NULL; - if (timeout != NULL) + __time64_t s = timeout != NULL ? timeout->tv_sec : 0; + int32_t us = timeout != NULL ? timeout->tv_usec : 0; + int32_t ns; + + if (s < 0 || us < 0) + return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL); + + /* Normalize the timeout, as legacy Linux __NR_select and __NR__newselect. + Different than syscall, it also handle possible overflow. */ + if (us / USEC_PER_SEC > INT64_MAX - s) { - ts64 = timeval64_to_timespec64 (*timeout); - pts64 = &ts64; + s = INT64_MAX; + ns = NSEC_PER_SEC - 1; } + else + { + s += us / USEC_PER_SEC; + us = us % USEC_PER_SEC; + ns = us * NSEC_PER_USEC; + } + + struct __timespec64 ts64, *pts64 = NULL; + if (timeout != NULL) + { + ts64.tv_sec = s; + ts64.tv_nsec = ns; + pts64 = &ts64; + } #ifndef __NR_pselect6_time64 # define __NR_pselect6_time64 __NR_pselect6 @@ -52,10 +74,13 @@ __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, (though the pselect() glibc call suppresses this behavior). Since select() on Linux has the same behavior as the pselect6 syscall, we update the timeout here. */ - if (r == 0 || errno != ENOSYS) + if (r >= 0 || errno != ENOSYS) { if (timeout != NULL) - TIMEVAL_TO_TIMESPEC (timeout, &ts64); + { + timeout->tv_sec = ts64.tv_sec; + timeout->tv_usec = ts64.tv_nsec / NSEC_PER_USEC; + } return r; } @@ -64,14 +89,15 @@ __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, #ifndef __ASSUME_TIME64_SYSCALLS struct timespec ts32, *pts32 = NULL; - if (timeout != NULL) + if (pts64 != NULL) { - if (! in_time_t_range (timeout->tv_sec)) + if (! in_time_t_range (pts64->tv_sec)) { __set_errno (EINVAL); return -1; } - ts32 = valid_timespec64_to_timespec (ts64); + ts32.tv_sec = s; + ts32.tv_nsec = ns; pts32 = &ts32; } # ifndef __ASSUME_PSELECT